libbb/read_key.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) 2008 Rob Landley <rob@landley.net>
   6  * Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
   7  *
   8  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
   9  */
  10 #include "libbb.h"
  11
  12 int64_t FAST_FUNC read_key(int fd, char *buffer)
  13 {
  14         struct pollfd pfd;
  15         const char *seq;
  16         int n;
  17
  18         /* Known escape sequences for cursor and function keys */
  19         static const char esccmds[] ALIGN1 = {
  20                 'O','A'        |0x80,KEYCODE_UP      ,
  21                 'O','B'        |0x80,KEYCODE_DOWN    ,
  22                 'O','C'        |0x80,KEYCODE_RIGHT   ,
  23                 'O','D'        |0x80,KEYCODE_LEFT    ,
  24                 'O','H'        |0x80,KEYCODE_HOME    ,
  25                 'O','F'        |0x80,KEYCODE_END     ,
  26 #if 0
  27                 'O','P'        |0x80,KEYCODE_FUN1    ,
  28                 /* [ESC] ESC O [2] P - [Alt-][Shift-]F1 */
  29                 /* ESC [ O 1 ; 2 P - Shift-F1 */
  30                 /* ESC [ O 1 ; 3 P - Alt-F1 */
  31                 /* ESC [ O 1 ; 4 P - Alt-Shift-F1 */
  32                 /* ESC [ O 1 ; 5 P - Ctrl-F1 */
  33                 /* ESC [ O 1 ; 6 P - Ctrl-Shift-F1 */
  34                 'O','Q'        |0x80,KEYCODE_FUN2    ,
  35                 'O','R'        |0x80,KEYCODE_FUN3    ,
  36                 'O','S'        |0x80,KEYCODE_FUN4    ,
  37 #endif
  38                 '[','A'        |0x80,KEYCODE_UP      ,
  39                 '[','B'        |0x80,KEYCODE_DOWN    ,
  40                 '[','C'        |0x80,KEYCODE_RIGHT   ,
  41                 '[','D'        |0x80,KEYCODE_LEFT    ,
  42                 /* ESC [ 1 ; 2 x, where x = A/B/C/D: Shift-<arrow> */
  43                 /* ESC [ 1 ; 3 x, where x = A/B/C/D: Alt-<arrow> */
  44                 /* ESC [ 1 ; 4 x, where x = A/B/C/D: Alt-Shift-<arrow> */
  45                 /* ESC [ 1 ; 5 x, where x = A/B/C/D: Ctrl-<arrow> - implemented below */
  46                 /* ESC [ 1 ; 6 x, where x = A/B/C/D: Ctrl-Shift-<arrow> */
  47                 '[','H'        |0x80,KEYCODE_HOME    , /* xterm */
  48                 /* [ESC] ESC [ [2] H - [Alt-][Shift-]Home */
  49                 '[','F'        |0x80,KEYCODE_END     , /* xterm */
  50                 '[','1','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
  51                 '[','2','~'    |0x80,KEYCODE_INSERT  ,
  52                 /* ESC [ 2 ; 3 ~ - Alt-Insert */
  53                 '[','3','~'    |0x80,KEYCODE_DELETE  ,
  54                 /* [ESC] ESC [ 3 [;2] ~ - [Alt-][Shift-]Delete */
  55                 /* ESC [ 3 ; 3 ~ - Alt-Delete */
  56                 /* ESC [ 3 ; 5 ~ - Ctrl-Delete */
  57                 '[','4','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
  58                 '[','5','~'    |0x80,KEYCODE_PAGEUP  ,
  59                 /* ESC [ 5 ; 3 ~ - Alt-PgUp */
  60                 /* ESC [ 5 ; 5 ~ - Ctrl-PgUp */
  61                 /* ESC [ 5 ; 7 ~ - Ctrl-Alt-PgUp */
  62                 '[','6','~'    |0x80,KEYCODE_PAGEDOWN,
  63                 '[','7','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
  64                 '[','8','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
  65 #if 0
  66                 '[','1','1','~'|0x80,KEYCODE_FUN1    ,
  67                 '[','1','2','~'|0x80,KEYCODE_FUN2    ,
  68                 '[','1','3','~'|0x80,KEYCODE_FUN3    ,
  69                 '[','1','4','~'|0x80,KEYCODE_FUN4    ,
  70                 '[','1','5','~'|0x80,KEYCODE_FUN5    ,
  71                 /* [ESC] ESC [ 1 5 [;2] ~ - [Alt-][Shift-]F5 */
  72                 '[','1','7','~'|0x80,KEYCODE_FUN6    ,
  73                 '[','1','8','~'|0x80,KEYCODE_FUN7    ,
  74                 '[','1','9','~'|0x80,KEYCODE_FUN8    ,
  75                 '[','2','0','~'|0x80,KEYCODE_FUN9    ,
  76                 '[','2','1','~'|0x80,KEYCODE_FUN10   ,
  77                 '[','2','3','~'|0x80,KEYCODE_FUN11   ,
  78                 '[','2','4','~'|0x80,KEYCODE_FUN12   ,
  79                 /* ESC [ 2 4 ; 2 ~ - Shift-F12 */
  80                 /* ESC [ 2 4 ; 3 ~ - Alt-F12 */
  81                 /* ESC [ 2 4 ; 4 ~ - Alt-Shift-F12 */
  82                 /* ESC [ 2 4 ; 5 ~ - Ctrl-F12 */
  83                 /* ESC [ 2 4 ; 6 ~ - Ctrl-Shift-F12 */
  84 #endif
  85                 /* '[','1',';','5','A' |0x80,KEYCODE_CTRL_UP   , - unused */
  86                 /* '[','1',';','5','B' |0x80,KEYCODE_CTRL_DOWN , - unused */
  87                 '[','1',';','5','C' |0x80,KEYCODE_CTRL_RIGHT,
  88                 '[','1',';','5','D' |0x80,KEYCODE_CTRL_LEFT ,
  89                 0
  90                 /* ESC [ Z - Shift-Tab */
  91         };
  92
  93         buffer++; /* saved chars counter is in buffer[-1] now */
  94
  95  start_over:
  96         errno = 0;
  97         n = (unsigned char)buffer[-1];
  98         if (n == 0) {
  99                 /* If no data, block waiting for input.
 100                  * It is tempting to read more than one byte here,
 101                  * but it breaks pasting. Example: at shell prompt,
 102                  * user presses "c","a","t" and then pastes "\nline\n".
 103                  * When we were reading 3 bytes here, we were eating
 104                  * "li" too, and cat was getting wrong input.
 105                  */
 106                 n = safe_read(fd, buffer, 1);
 107                 if (n <= 0)
 108                         return -1;
 109         }
 110
 111         {
 112                 unsigned char c = buffer[0];
 113                 n--;
 114                 if (n)
 115                         memmove(buffer, buffer + 1, n);
 116                 /* Only ESC starts ESC sequences */
 117                 if (c != 27) {
 118                         buffer[-1] = n;
 119                         return c;
 120                 }
 121         }
 122
 123         /* Loop through known ESC sequences */
 124         pfd.fd = fd;
 125         pfd.events = POLLIN;
 126         seq = esccmds;
 127         while (*seq != '\0') {
 128                 /* n - position in sequence we did not read yet */
 129                 int i = 0; /* position in sequence to compare */
 130
 131                 /* Loop through chars in this sequence */
 132                 while (1) {
 133                         /* So far escape sequence matched up to [i-1] */
 134                         if (n <= i) {
 135                                 /* Need more chars, read another one if it wouldn't block.
 136                                  * Note that escape sequences come in as a unit,
 137                                  * so if we block for long it's not really an escape sequence.
 138                                  * Timeout is needed to reconnect escape sequences
 139                                  * split up by transmission over a serial console. */
 140                                 if (safe_poll(&pfd, 1, 50) == 0) {
 141                                         /* No more data!
 142                                          * Array is sorted from shortest to longest,
 143                                          * we can't match anything later in array -
 144                                          * anything later is longer than this seq.
 145                                          * Break out of both loops. */
 146                                         goto got_all;
 147                                 }
 148                                 errno = 0;
 149                                 if (safe_read(fd, buffer + n, 1) <= 0) {
 150                                         /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
 151                                          * in fact, there is no data. */
 152                                         if (errno != EAGAIN) {
 153                                                 /* otherwise: it's EOF/error */
 154                                                 buffer[-1] = 0;
 155                                                 return -1;
 156                                         }
 157                                         goto got_all;
 158                                 }
 159                                 n++;
 160                         }
 161                         if (buffer[i] != (seq[i] & 0x7f)) {
 162                                 /* This seq doesn't match, go to next */
 163                                 seq += i;
 164                                 /* Forward to last char */
 165                                 while (!(*seq & 0x80))
 166                                         seq++;
 167                                 /* Skip it and the keycode which follows */
 168                                 seq += 2;
 169                                 break;
 170                         }
 171                         if (seq[i] & 0x80) {
 172                                 /* Entire seq matched */
 173                                 n = 0;
 174                                 /* n -= i; memmove(...);
 175                                  * would be more correct,
 176                                  * but we never read ahead that much,
 177                                  * and n == i here. */
 178                                 buffer[-1] = 0;
 179                                 return (signed char)seq[i+1];
 180                         }
 181                         i++;
 182                 }
 183         }
 184         /* We did not find matching sequence.
 185          * We possibly read and stored more input in buffer[] by now.
 186          * n = bytes read. Try to read more until we time out.
 187          */
 188         while (n < KEYCODE_BUFFER_SIZE-1) { /* 1 for count byte at buffer[-1] */
 189                 if (safe_poll(&pfd, 1, 50) == 0) {
 190                         /* No more data! */
 191                         break;
 192                 }
 193                 errno = 0;
 194                 if (safe_read(fd, buffer + n, 1) <= 0) {
 195                         /* If EAGAIN, then fd is O_NONBLOCK and poll lied:
 196                          * in fact, there is no data. */
 197                         if (errno != EAGAIN) {
 198                                 /* otherwise: it's EOF/error */
 199                                 buffer[-1] = 0;
 200                                 return -1;
 201                         }
 202                         break;
 203                 }
 204                 n++;
 205                 /* Try to decipher "ESC [ NNN ; NNN R" sequence */
 206                 if (ENABLE_FEATURE_EDITING_ASK_TERMINAL
 207                  && n >= 5
 208                  && buffer[0] == '['
 209                  && buffer[n-1] == 'R'
 210                  && isdigit(buffer[1])
 211                 ) {
 212                         char *end;
 213                         unsigned long row, col;
 214
 215                         row = strtoul(buffer + 1, &end, 10);
 216                         if (*end != ';' || !isdigit(end[1]))
 217                                 continue;
 218                         col = strtoul(end + 1, &end, 10);
 219                         if (*end != 'R')
 220                                 continue;
 221                         if (row < 1 || col < 1 || (row | col) > 0x7fff)
 222                                 continue;
 223
 224                         buffer[-1] = 0;
 225                         /* Pack into "1 <row15bits> <col16bits>" 32-bit sequence */
 226                         col |= (((-1 << 15) | row) << 16);
 227                         /* Return it in high-order word */
 228                         return ((int64_t) col << 32) | (uint32_t)KEYCODE_CURSOR_POS;
 229                 }
 230         }
 231  got_all:
 232
 233         if (n <= 1) {
 234                 /* Alt-x is usually returned as ESC x.
 235                  * Report ESC, x is remembered for the next call.
 236                  */
 237                 buffer[-1] = n;
 238                 return 27;
 239         }
 240
 241         /* We were doing "buffer[-1] = n; return c;" here, but this results
 242          * in unknown key sequences being interpreted as ESC + garbage.
 243          * This was not useful. Pretend there was no key pressed,
 244          * go and wait for a new keypress:
 245          */
 246         buffer[-1] = 0;
 247         goto start_over;
 248 }